Image projection apparatus and illumination optical system

Abstract

An image projection apparatus includes: an illumination optical system; a projection optical system assembled integrally with the illumination optical system; and a frame fixed to only one system, that has a larger weight, of the illumination optical system and the projection optical system.

The invention claimed is: 
     
       1. An image projection apparatus, comprising:
 an illumination optical system; 
 a projection optical system assembled integrally with the illumination optical system; and 
 a frame fixed to only the projection optical system, that has a larger weight, than the illumination optical system, 
 wherein the illumination optical system is not fixed to the frame and is fixed to the projection optical system which is fixed to the frame. 
 
     
     
       2. The image projection apparatus according to  claim 1 , wherein the illumination optical system includes a light source, and the light source includes one of a light emitting diode and a laser. 
     
     
       3. The image projection apparatus according to  claim 1 , wherein the projection optical system has a throw ratio of 0.75 or smaller. 
     
     
       4. The image projection apparatus according to  claim 1 , wherein the weight of the projection optical system is three times or more as the weight of the illumination optical system. 
     
     
       5. The image projection apparatus according to  claim 1 , further comprising a housing containing the illumination optical system, wherein
 the housing and the projection optical system are assembled integrally. 
 
     
     
       6. The image projection apparatus according to  claim 5 , wherein the housing is formed of metal. 
     
     
       7. The image projection apparatus according to  claim 1 , wherein the frame serves as an outer package containing the illumination optical system and the projection optical system. 
     
     
       8. The image projection apparatus according to  claim 1 , wherein the illumination optical system and the frame are provided to be away from each other without being in direct contact with each other. 
     
     
       9. The image projection apparatus according to  claim 2 , wherein the illumination optical system further includes an optical multiplexer and an optical modulator. 
     
     
       10. The image projection apparatus according to  claim 1 , wherein the illumination optical system and the projection optical system are indirectly fixed to each other with another component in between. 
     
     
       11. The image projection apparatus according to  claim 9 , wherein the illumination optical system and the projection optical system are fixed to each other to allow a surface of the illumination optical system and a surface of the projection optical system to be opposed to each other, the surface of the illumination optical system and the surface of the projection optical system each being parallel to a light axis. 
     
     
       12. The image projection apparatus according to  claim 9 , wherein the illumination optical system and the projection optical system are fixed to each other to allow a surface of the illumination optical system and a surface of the projection optical system to be opposed to each other, the surface of the illumination optical system and the surface of the projection optical system each being orthogonal to a light axis. 
     
     
       13. The image projection apparatus according to  claim 1 , wherein respective relative positions of the illumination optical system and the projection optical system are adjustable in a light axis direction. 
     
     
       14. An illumination optical system configured to be mounted on an image projection apparatus including a projection optical system and a frame,
 the illumination optical system being assembled integrally with the projection optical system, wherein 
 only the projection optical system, that has a larger weight than the illumination optical system, is fixed to the frame, 
 wherein the illumination optical system is not fixed to the frame and is fixed to the projection optical system which is fixed to the frame. 
 
     
     
       15. The image projection apparatus according to  claim 1 , wherein the illumination optical system and the frame are in indirect contact through the projection optical system.